I do a lot of shooting with a 12” straight blowback PCC AR with a Rex Silentium .458 MG7k. For comparison, I have or have access to, mostly .45 pistol cans, and a Dead Air Odessa. I have a pair of CGS MOD9s in purgatory, which does me no good. In other words, I don’t have much basis of comparison on this type of host.

Anyway, the .458 can does a pretty good job, but I sometimes find myself contemplating getting a 9mm twin, or perhaps something else along those lines. For better sound suppression, not that its really needed.

So my question is this: would a 9mm MG7k just increase blowback, making the gun dirtier and louder at the ear? Or is 9mm low pressure enough that that’s not a thing? Would the calculus change if the host was a radial-delayed blowback?